Does impaired executive functioning differentially impact verbal memory measures in older adults with suspected dementia?

The purpose of this study was to examine whether executive dysfunction differentially impacts list-learning and story recall tasks in a sample of older adults referred for suspected cognitive impairment. Older adults (N = 61) with mild cognitive impairment (MCI) or probable mild dementia, and those who did not meet criteria for diagnosis of dementia, were assessed using measures of executive function and verbal memory. Two groups were established based on performance on measures of executive function: (a) the No Executive Dysfunction group (NoED; n = 33) consisted of persons without impairment on any obtained measures of executive function; and (b) the Executive Dysfunction group (ED; n = 28) contained persons with impairment on at least one of the measures of executive function. The two groups were compared on performance on two measures of verbal memory, the California Verbal Learning Test-II (CVLT-II) and the Logical Memory (LM) subtest from the Wechsler Memory Scale-Revised (WMS-R). The NoED group performed significantly better than the ED group on the total learning and short delay free recall trials of the CVLT-II. However, there were no significant differences between the groups on the other indices of the CVLT-II (i.e., long delay free recall, recognition, recall repetitions, recall intrusions, or recognition false-positives) or on the immediate and delayed recall trials of the LM measure. These results support previous research demonstrating the impact of executive dysfunction on the acquisition of and short-delay retrieval of verbal information in older adults with suspected cognitive impairment.     

Learning Impairment is Associated With Recall Ability in Multiple Sclerosis

Recent evidence suggests that persons with multiple sclerosis may experience deficits in verbal and visuospatial acquisition rather than recall. The present study was designed to determine whether this finding generalized to a broader range of neuropsychological tests of learning and memory. To control for group differences in information acquisition, healthy controls (HCs) and persons with multiple sclerosis (MS) were trained to specific learning criteria on both verbal (i.e., paragraph learning and paired associates) and visuospatial (i.e., facial recognition) memory tasks. Persons with MS required significantly more learning trials to meet criteria on the paragraph learning and facial recognition tasks, but not the paired associates test. However, after learning comparable amounts of information, the MS and HC groups recalled statistically similar amounts of information at 30-minutes, 90-minutes, and up to 1-week on the paragraph learning and paired associate tests. This suggests that persons with MS may have deficits in acquisition rather than recall per se. Results are discussed in terms of possible rehabilitation strategies to improve memory functioning in persons with MS.     

Learning impairment is associated with recall ability in multiple sclerosis

Recent evidence suggests that persons with multiple sclerosis may experience deficits in verbal and visuospatial acquisition rather than recall. The present study was designed to determine whether this finding generalized to a broader range of neuropsychological tests of learning and memory. To control for group differences in information acquisition, healthy controls (HCs) and persons with multiple sclerosis (MS) were trained to specific learning criteria on both verbal (i.e., paragraph learning and paired associates) and visuospatial (i.e., facial recognition) memory tasks. Persons with MS required significantly more learning trials to meet criteria on the paragraph learning and facial recognition tasks, but not the paired associates test. However, after learning comparable amounts of information, the MS and HC groups recalled statistically similar amounts of information at 30-minutes, 90-minutes, and up to 1-week on the paragraph learning and paired associate tests. This suggests that persons with MS may have deficits in acquisition rather than recall per se. Results are discussed in terms of possible rehabilitation strategies to improve memory functioning in persons with MS.     

Postictal Courses of Cognitive Deficits in Focal Epilepsies

Summary: Patients with epileptic seizures frequently complain of long-lasting cognitive impairment after a seizure. We evaluated this issue in 31 patients with epileptic seizures of a frontal (n = 8) or temporal lobe origin [right temporal lobe (RTL) n = 8/left temporal lobe (LTL) n = 151. Seizures were secondarily generalized in 18 patients. Computerized testing of verbal and nonverbal recognition memory was performed before the seizure, directly after postictal reorientation, and 30 min and 1 h later. Repeated testing of 14 healthy persons served as control. The following results were obtained: Depending on seizure generalization, postictal reorientation times were 1–45 min. Frontal lobe seizures showed no effect on postictal memory performances, but verbal and visual recognition memory was significantly decreased after temporal lobe seizures. Decrease in either verbal or visual memory and time of recovery were related to lateralization of seizure onset. Functional recovery after reorientation lasted 30 min to 1 h. The decrease in performance was more severe after generalized seizures. Decision times during memory performance were not significantly affected by the seizures. Temporal lobe seizures lead to circumscribed and long-lasting memory deficits, which can be assumed to affect patients'capabilities seriously. Preand postictal testing is a useful tool for determining postictal cognitive impairment and in determining the site of seizure onset.     

Cognitive Consequences of Two-Thirds Anterior Temporal Lobectomy on Verbal Memory in 144 Patients: A Three-Month Follow-Up Study

Previous studies have shown that left temporal lobectomy for intractable epilepsy can lead to verbal memory deficits. However, patients with left temporal lobe epilepsy (LTLE) frequently have impaired verbal memory preoperativel. The present analysis of 144 patients who underwent temporal lobe resections for either left (n = 68) or right (n = 76) temporal lobe epilepsy (LTLE, RTLE) addressed the questions of (a) whether a left two-thirds anterior temporal lobectomy (ATL) increases deficits in these qualitative aspects of verbal memory already impaired preoperatively, and (b) whether other aspects of verbal memory are additionally affected. We also evaluated possible determinants of preoperative abilities and postoperative changes, using multiple regression analysis. Preoperatively, patients with LTLE differed from patients with RTLE only in poorer performance on measures of long-term consolidation/retrieval (delayed recall). This was related to hippocampal pathology and seizure severity. Only left temporal lobe resections resulted in significant deterioration in verbal learning and memory. Acquisition over learning trials and recognition deteriorated most markedly, whereas performance in long-term consolidation/retrieval showed only minor changes. Preoperative performance levels, chronological age, the extent of the en bloc resection, preoperative performance on figural memory, and preoperative seizure severity were valuable determinants of postoperative changes in acquisition and recognition. In contrast, changes in consolidation/retrieval related only to preoperative ability. Left two-thirds ATL leads to new impairment in addition to preexisting memory deficits. The finding that left temporal lobectomy affects verbal acquisition and recognition more than long-term consolidatiodretrieval, including the different determinants of these changes, most likely reflects the differential effects of surgery on mesial temporal and neocortical temporal functions.     

Differential patterns of memory performance in relapsing, remitting and secondary progressive multiple sclerosis

BACKGROUND: Memory dysfunction is common in multiple sclerosis (MS). A retrieval failure has been reported as the primary cause for the memory deficits, although some studies also described a faulty acquisition. AIMS: The aim of the study was to examine memory function in relapsing remitting (RR) and secondary progressive (SP) MS patients, analyze the patterns of performance and to investigate whether disease course influences this performance. DESIGN AND SETTINGS: Case-control prospective study conducted in a clinical setting. MATERIALS AND METHODS: Fifty-five RR, 23 SP MS patients and 80 normal subjects were evaluated with a comprehensive neuropsychological battery. Memory was assessed with tasks from the Signoret memory battery. Attention and executive function were also assessed. STATISTICAL ANALYSIS: Univariate analysis of variance, Mann-Whitney U-test, multivariate logistic regression and Chi-square test were used as appropriate. RESULTS: MS patients performed significantly worse than controls on almost all measures of memory (P < 0,001). MS subgroups differed in tasks of delayed recall (logical memory- P =0,019; wordlist delayed recall, P < 0,001), semantic cued recall (P < 0,001), recognition trials (P =0,006) rate of forgetting (P < 0,001) and confabulation and intrusion errors (P =0,004). CONCLUSIONS: Memory is consistently impaired in MS patients and disease course differentially affects the pattern of performance. SP patients show greater difficulties and a more pervasive pattern of dysfunction than RR patients. Delayed recall was the most affected memory measure and performance on this task discriminates between RR and SP MS patients. Relapsing remitting patients performed within the mildly impaired range while SP patients showed a moderate to severe impairment.     

Memory evaluation in mild cognitive impairment using recall and recognition tests

Amnestic mild cognitive impairment (MCI) is a selective episodic memory deficit that often indicates early Alzheimer's disease. Episodic memory function in MCI is typically defined by deficits in free recall, but can also be tested using recognition procedures. To assess both recall and recognition in MCI, MCI (n = 21) and older comparison (n = 30) groups completed the USC-Repeatable Episodic Memory Test. Subjects memorized two verbally presented 15-item lists. One list was used for three free recall trials, immediately followed by yes/no recognition. The second list was used for three-alternative forced-choice recognition. Relative to the comparison group, MCI had significantly fewer hits and more false alarms in yes/no recognition, and were less accurate in forced-choice recognition. Signal detection analysis showed that group differences were not due to response bias. Discriminant function analysis showed that yes/no recognition was a better predictor of group membership than free recall or forced-choice measures. MCI subjects recalled fewer items than comparison subjects, with no group differences in repetitions, intrusions, serial position effects, or measures of recall strategy (subjective organization, recall consistency). Performance deficits on free recall and recognition in MCI suggest a combination of both tests may be useful for defining episodic memory impairment associated with MCI and early Alzheimer's disease.     

Executive dysfunction in patients with spinocerebellar ataxia type 3

The aim of this study was to assess the cognitive functions of patients with spinocerebellar ataxia type 3(SCA3). We examined 15 patients with genetically confirmed SCA3 and 15 healthy control subjects matched for age, years of education, and intellectual ability. We administered verbal memory (word recall and word recognition) and executive function tasks (word fluency test, forward and backward digit and visual span tests, Kana Pick-out Test, Trail Making Test, and conflicting instructions and a Go/NoGo task from the Frontal Assessment Battery). We found that patients with SCA3 had significantly lower scores than the healthy control subjects on the word recall, semantic, and letter fluency, and backward digit span tests, while word recognition was well preserved. The other executive function tests showed preserved functions in the SCA3 group, indicating that visual working memory, and attention and inhibition control were not affected. The patients with SCA3 showed impaired word recall and intact word recognition, and accordingly, episodic memory encoding and storage processes in short-term memory were preserved. In category and letter-fluency tests, impairment was attributable to word-retrieval from semantic memory. Impaired verbal working memory may be involved in the retrieval of verbal information from phonological storage by means of continuous subvocal rehearsal, rather than a deficit in initial phonological encoding. Essential executive dysfunction in patients with SCA3 may be due to damage in the cerebellar cortex–ventral dentate nucleus–thalamus–prefrontal cortex circuits, which are involved in strategic retrieval of verbal information from different modes of memory storage.     

Effects of scopolamine on verbal memory; a retrieval or acquisition deficit?

This study examines the relationship between encoding and retrieval factors in producing the well-documented scopolamine-induced deficits in verbal memory. Subjects were required to learn word lists of 10 items, and were given a total of 8 acquisition trials per list. While the placebo group achieved criterion within 4 acquisition trials, the group treated with scopolamine failed to reach criterion at all, with recall levelling off within 4 acquisition trials. Acquisition curves for subjects treated with scopolamine paralleled those obtained for the placebo group. Performance on delayed recall and recognition tests indicated that the subjects had in fact successfully encoded items in long-term memory, but had been unable to retrieve them in free recall. The results suggest a retrieval problem in what has traditionally been considered a scopolamine-induced encoding deficit. We suggest that scopolamine may disrupt the organization of material at input, so that items which have achieved durable storage are not accessible for free recall.     

Implicit and explicit memory functioning in children with heavy prenatal alcohol exposure.

Prenatal alcohol exposure is associated with widespread and devastating neurodevelopmental deficits. Numerous reports have suggested memory deficits in both humans and animals exposed prenatally to alcohol. However, the nature of these memory deficits remains to be characterized. Recently children with fetal alcohol syndrome were shown to have learning and memory deficits on a verbal learning and memory measure that involved free recall and recognition memory. The current study seeks to further characterize memory functioning in children with heavy prenatal alcohol exposure by evaluating priming performance. The choice of task is also relevant given previous studies of memory performance in patient groups with and without involvement of the basal ganglia, a group of structures known to be affected in fetal alcohol syndrome. Three groups were evaluated for lexical priming, free recall, recognition memory, and verbal fluency: (1) children with heavy prenatal alcohol exposure; (2) children with Down syndrome; and (3) nonexposed controls. The children with Down syndrome showed significantly less priming than alcohol-exposed children, who did not differ from controls. In addition, the alcohol-exposed children were impaired on the free recall task but not on the recognition memory task, whereas the children with Down syndrome performed significantly worse than the alcohol-exposed group on both tasks. Finally, on the verbal fluency task, children with heavy prenatal alcohol exposure were impaired on both category and letter fluency, but the degree of impairment was greater for letter fluency. These results further characterize the memory deficits in children with heavy prenatal alcohol exposure suggesting that in spite of learning and memory deficits, they are able to benefit from priming of verbal information.     

Acquisition, recall, and forgetting of verbal information in long-term memory by young, middle-aged, and elderly individuals

Memory performance by four age groups (30-45 years, 46-60 years, 61-75 years, and 76-90 years) was compared on a multi-trial verbal recall task with 20-minute and 1-day delay free recall and recognition trials. The rate of acquisition across 5 learning trials was similar for all ages except the youngest group whose performance was constrained by a ceiling effect. The level of acquisition achieved was less in the two oldest groups. Words gained across trials and words lost across trials made similar contributions to the shape of the learning curve for the acquisition trials. Subjective organization decreased with age, but remained strongly related to the number of words recalled during acquisition for all age groups. The two oldest age groups demonstrated significant declines in words recalled on the 20-minute and 1-day delay trials. A subset of the oldest group demonstrated more rapid forgetting at the 1-day delay when participants from all age conditions were matched on acquisition. Thus, many aspects of free recall were impaired with age, and variance measurement of recall showed greater inter-individual differences with increasing age. This increase in individual differences could reflect a single form of age-related memory impairment, or it could indicate that memory impairment in the elderly is due to multiple processes. The importance of testing across the life span and using tests that examine a variety of memory components and processes for establishing norms and clarifying age- related deficits are discussed.     

Memory impairment following right hemisphere stroke: a comparative meta-analytic and narrative review

We examined the evidence for widely held clinical beliefs about memory impairment following right hemisphere stroke (RHS), conducting both narrative and meta-analytic reviews of the literature [MEDLINE (1966-January 2003), PsycINFO (1974-January 2003), and CINAHL (1982-December 2002)]. We sought to determine whether RHS patients experience more problems with non-verbal memory than non-stroke controls (NSCs) and left hemisphere stroke (LHS) patients. Secondarily, we sought to determine whether RHS patients experience more problems with verbal memory than NSCs and fewer verbal memory problems than LHS patients. We also examined the effect of type of memory assessment (recall versus recognition) on reported findings. As regards non-verbal memory, narrative and meta-analytic reviews found that RHS patients had deficits relative to NSCs, on tests of both recall and recognition. The evidence for RHS non-verbal memory deficits relative to LHS was mixed in the narrative review, whereas the meta-analysis found RHS deficits on non-verbal recognition tests, but no difference between RHS and LHS patients on non-verbal recall tests. Deficits on recognition tests imply problems with early encoding of material or possibly its storage. Regarding verbal memory, the narrative review found that RHS patients performed more poorly than NSCs in about half of all studies. The meta-analytic review confirmed poorer RHS performance on tests of verbal recall, but none of the studies that compared RHS and NSCs on verbal recognition could be included in this type of review. The narrative review found mixed evidence as regards the performance of RHS and LHS patients on verbal memory tests, but the meta-analysis pointed to RHS superiority for both verbal recall and recognition. The relative strengths of both types of review are discussed.     

Effectiveness of the Rey-Osterrieth Complex Figure Test and the Meyers and Meyers Recognition Trial in the Detection of Suspect Effort

The Rey-Osterrieth Complex Figure Test (ROCFT) is a popular measure of visuoconstructive skills and visual memory. A recognition memory trial was recently developed by Meyers and Meyers (1995) and attached to the standard administration of the ROCFT. The addition of this recognition paradigm (comprised of 12 small designs from the original ROCFT stimulus interspersed among 12 foils) makes ROCFT a potentially useful instrument in capturing suspect effort because patients attempting to feign memory difficulties typically operate from the misconception that recognition memory is as impaired as free recall in brain injury and, as a result, suppress recognition performance. The ROCFT (copy, immediate recall [i.e., 3-min recall], and the recognition trial) was administered to four sets of participants: 58 patients with suspect effort; 23 neuropsychology clinic patients with verbal memory impairment, 17 clinic patients with visual memory impairment, and 30 clinic patients without memory impairment. Group comparisons revealed significant group differences in direct copy, immediate recall, and recognition scores of the ROCFT (p &lt;.0001), with the suspect effort group displaying significantly lower performance on the copy and immediate recall scores than the verbal memory impaired and nonmemory impaired clinic patient groups, and significantly lower recognition scores than all three clinical groups. Furthermore, qualitative examination of the recognition trial revealed the presence of “atypical recognition errors” that were endorsed with significantly higher frequency by the suspect effort patients. A combination score incorporating the copy, true positive recognition, and atypical recognition error scores yielded a sensitivity of 74% while misclassifying only approximately 4% of verbal memory impaired clinic patients, 12% of visual memory impaired clinic patients, and 3% of nonmemory impaired clinic patients. Thus, the ROCFT + recognition trial show considerable potential for detecting noncredible effort.     

Effectiveness of the Rey-Osterrieth Complex Figure Test and the Meyers and Meyers recognition trial in the detection of suspect effort

The Rey-Osterrieth Complex Figure Test (ROCFT) is a popular measure of visuoconstructive skills and visual memory. A recognition memory trial was recently developed by Meyers and Meyers (1995) and attached to the standard administration of the ROCFT. The addition of this recognition paradigm (comprised of 12 small designs from the original ROCFT stimulus interspersed among 12 foils) makes ROCFT a potentially useful instrument in capturing suspect effort because patients attempting to feign memory difficulties typically operate from the misconception that recognition memory is as impaired as free recall in brain injury and, as a result, suppress recognition performance. The ROCFT (copy, immediate recall [i.e., 3-min recall], and the recognition trial) was administered to four sets of participants: 58 patients with suspect effort; 23 neuropsychology clinic patients with verbal memory impairment, 17 clinic patients with visual memory impairment, and 30 clinic patients without memory impairment. Group comparisons revealed significant group differences in direct copy, immediate recall, and recognition scores of the ROCFT (p<.0001), with the suspect effort group displaying significantly lower performance on the copy and immediate recall scores than the verbal memory impaired and nonmemory impaired clinic patient groups, and significantly lower recognition scores than all three clinical groups. Furthermore, qualitative examination of the recognition trial revealed the presence of "atypical recognition errors" that were endorsed with significantly higher frequency by the suspect effort patients. A combination score incorporating the copy, true positive recognition, and atypical recognition error scores yielded a sensitivity of 74% while misclassifying only approximately 4% of verbal memory impaired clinic patients, 12% of visual memory impaired clinic patients, and 3% of nonmemory impaired clinic patients. Thus, the ROCFT+recognition trial show considerable potential for detecting noncredible effort.     

Schizophrenia patients demonstrate a dissociation on declarative and non-declarative memory tests

Declarative memory refers to the recall and recognition of factual information. In contrast, non-declarative memory entails a facilitation of memory based on prior exposure and is typically assessed with priming and perceptual-motor sequencing tasks. In this study, schizophrenia patients were compared to normal comparison subjects on two computerized memory tasks: the Word-stem Priming Test (n=30) and the Pattern Sequence Learning Test (n=20). Word-stem Priming includes recall, recognition (declarative) and priming (non-declarative) components of memory. The schizophrenia patients demonstrated an impaired performance on recall of words with relative improvement during the recognition portion of the test. Furthermore, they performed normally on the priming portion of the test. Thus, on tests of declarative memory, the patients had retrieval deficits with intact performance on the non-declarative memory component. The Pattern Sequence Learning Test utilizes a serial reaction time paradigm to assess non-declarative memory. The schizophrenia patients' serial reaction time was significantly slower than that of comparison subjects. However, the patients' rate of acquisition was not different from the normal comparison group. The data suggest that patients with schizophrenia process more slowly than normal, but have an intact non-declarative memory. The schizophrenia patients' dissociation on declarative vs. non-declarative memory tests is discussed in terms of possible underlying structural impairment.     

Verbal learning and memory deficits in Mild Cognitive Impairment

Criteria for amnestic MCI rely on the use of delayed recall tasks to establish the presence of memory impairment. This study applied the California Verbal Learning Test to detail memory performance in MCI patients (n=70), as compared to control subjects (n=92) and AD patients (n=21). Learning across the 5 trials was different among the 3 groups. Learning strategy was also different, the MCI group showing less semantic clustering than the control group. However, both MCI patients and controls could benefit from semantic cueing. This study showed that beyond consolidation deficits, MCI patients have marked difficulties in acquisition and recall strategies.     

On the nature of memory disturbance in multiple sclerosis

Thirty-seven patients with multiple sclerosis (MS) were compared to 26 normal controls of equivalent age, education, and verbal intelligence on measures of verbal learning and memory (Digit Span and Supraspan, Brown-Peterson Distractor Task, Selective Reminding Test, Story Recall, and Free Verbal Recall) and verbal fluency (Letter and Animal Fluency). The MS patients exhibited deficits on measures of secondary (long-term) memory and verbal fluency, but performed normally on measures of primary (short-term) memory, recognition memory, and rate of forgetting from secondary memory. These results suggest that the memory disturbance in MS results primarily from an imparied ability to access information from secondary memory, while encoding and storage capacity is intact. Degree of memory impairment was unrelated to length of illness, severity of disability, or self-reported depression.     

On the nature of memory disturbance in multiple sclerosis

Abstract

Thirty-seven patients with multiple sclerosis (MS) were compared to 26 normal controls of equivalent age, education, and verbal intelligence on measures of verbal learning and memory (Digit Span and Supraspan, Brown-Peterson Distractor Task, Selective Reminding Test, Story Recall, and Free Verbal Recall) and verbal fluency (Letter and Animal Fluency). The MS patients exhibited deficits on measures of secondary (long-term) memory and verbal fluency, but performed normally on measures of primary (short-term) memory, recognition memory, and rate of forgetting from secondary memory. These results suggest that the memory disturbance in MS results primarily from an impaired ability to access information from secondary memory, while encoding and storage capacity is intact. Degree of memory impairment was unrelated to length of illness, severity of disability, or self-reported depression.     

Distinct memory profiles in Alzheimer's disease

Memory impairment is a prominent defining feature of Alzheimer's disease (AD), yet the degree to which the profile of memory impairment is uniform across patients is not fully resolved. The study examined patterns of memory impairment in a large cohort of AD patients, with particular attention to the relationship between working and long-term declarative memory. Tests of working memory, visual and verbal recall and recognition, and recent personal memory were administered to 67 AD patients in the early to moderate stages of disease and to 30 age-matched controls. Performance on all measures was significantly poorer in patients than in controls. Factor analysis of test scores delineated five factors representing the domains of working memory, visual recall, verbal recall, recognition, and personal memory, indicating that these aspects of memory can break down separately. Cluster analysis revealed distinct memory profiles. Some patients showed predominant problems in working memory, with relatively superior long term retention, whereas other patients showed the reverse pattern. Qualitatively distinct profiles arose at comparable levels of severity. Problems in working memory, but not long term memory were associated with the presence of language and perceptuospatial deficits. The results reinforce previous findings that both working and long term memory failure contribute to the memory symptoms of AD patients, and demonstrate dissociations in memory breakdown across the cohort. The link between working memory and language performance, together with findings of posterior hemisphere abnormalities on neuroimaging, lead us to reassess the nature of working memory deficits in AD.     

Memory functions in aphasic and non-aphasic stroke patients

Abstract

We studied selected memory functions in 15 left-hemisphere stroke patients with aphasia, five non-aphasic left-hemisphere stroke patients, 16 right-hemisphere stroke patients and 10 normal controls. Memory was tested systematically for immediate recall of digits and letters, short-term (15 s) recognition of auditory and visual words and of non-verbal designs, and long-term (15 s) recognition of auditory and visual words. CT scan lesion localizations were recorded for all stroke patients. The aphasic group was deficient on immediate and short-term auditory and visual verbal memory tasks, while the right hemisphere group was inferior on both visual non-verbal patterns. Of non-aphasic left-hemisphere stroke patients, only a single patient with a left temporo-occipital lesion showed immediate and short-term verbal memory deficits. Right and left hemisphere aphasic stroke patients with isolated subcortical lesions demonstrated memory impairment, though to a lesser extent than patients with cortical lesions. All groups of stroke patients were deficient on long-term auditory and visual verbal memory. The results are discussed in terms of cerebral localization of memory functions and of the relationships of aphasia to memory dysfunction.